A pellicle device is obtained by bonding a transparent optical thin film (pellicle film) to a pellicle frame having a shape corresponding to that of a photomask or a reticle, while expanding the film. The pellicle device prevents foreign materials from directly adhering onto the photomask or the reticle. In addition, even when the foreign materials adhere onto the pellicle film, such foreign materials do not form images on a semiconductor substrate or the like. Therefore, it is possible to accurately transfer a circuit pattern, and thus improve a manufacturing yield in a photolithography step.
In recent years, along with high integration of a semiconductor device or the like, a circuit pattern has been required to be drawn more finely with a lower line width, and a mainstream exposure light source to be used in the photolithography step has employed a short-wavelength light. The light source employing such short-wavelength light has a high output power and high light energy. Therefore, when an inorganic acid such as sulfuric acid or phosphoric acid remains in an anodic oxide film on a surface of an aluminum frame material for forming the pellicle frame, there arises a problem in that such inorganic acid reacts with a basic substance such as ammonia present in an exposure atmosphere to generate a reaction product such as ammonium sulfate, and the reaction product (haze) causes fogging and affects a transferred image.
In view of the foregoing, there has been proposed a pellicle frame that is obtained by forming an anodic oxide film on a surface of an aluminum frame material through anodic oxidation processing using an electrolytic solution containing tartaric acid or a salt thereof, and thus reduces an amount of an inorganic acid such as sulfuric acid or phosphoric acid and suppresses generation of haze as much as possible even under irradiation with high-energy light (see Patent Literature 1).
Meanwhile, it is necessary to strictly control particles in a manufacturing process of the semiconductor device or the like, and also the pellicle device is generally confirmed for the presence or absence of dust by visual observation or with an inspection device. At this time, there is a problem in that a film defect visually observed as a white spot on a surface of the pellicle frame is confusable with fine dust, and thus an inspection operation is disturbed.
There has been reported that, on the assumption that such film defect visually observed as a white spot is caused by a crystallized product contained in a metal structure forming the aluminum frame material being corroded with a dye solution in dyeing of the anodic oxide film in black and dropped out from the anodic oxide film, dye missing or generation of a white spot can be reduced by specifying a component composition of a JIS 7075 aluminum alloy for forming the aluminum frame material and further shaking the aluminum frame material in the dye solution at the time of dyeing of the aluminum frame material with a black-based dye after anodic oxidation processing (see Patent Literature 2).
However, the thinning of the circuit pattern in the semiconductor device or the like as described above has increasingly progressed, and along with this, inspection standards for the pellicle device have become stricter. Therefore, a white spot involving light reflection in visual inspection not only under irradiation with fluorescent light but also under irradiation with collected light, that is, a surface glittering defect of the pellicle frame under irradiation with collected light is required to be reduced because such defect may be falsely recognized as dust.